Osteoporosis a condition in which bone mass is reduced, increasing the risk for developing fractures. Osteoporosis reflects the inadequate accumulation of bone tissue during growth and maturation, excessive losses thereafter or both. Bone mass is one of the main determinants of osteoporotic fracture. Recently it has been reported that bone mass correlates to a genetic component which can be ascribed largely to a allelic change in the receptor for calcitriol (1,25 dihydroxyvitamin d).